The silicide LiRh₂Si₂ was synthesized from the elements in a sealed niobium ampoule and was characterized by X-ray powder and single-crystal diffraction: FeMo₂B₂ type (ordered version of U₃Si₂), <i>P</i>4/<i>mbm</i>, <i>a</i> = 698.1(5), <i>c</i> = 274.6(4) pm, <i>wR</i>2 = 0.0842, 186 <i>F</i>² values and 11 variables. The rhodium and silicon atoms build up a covalently bonded three-dimensional [Rh₂Si₂] network (244-248 pm Rh-Si), in which the lithium atoms fill larger channels which extend along the <i>c</i> axis. A similar structural arrangement occurs in LiY₂Si₂, however, the strong difference in size between rhodium and yttrium leads to different distortions. LiRh₂Si₂ and LiY₂Si₂ are isopointal rather than isotypic. The crystal chemistry and bonding peculiarities of both silicides are discussed on the basis of ab initio electronic structure calculations. ⁷Li solid-state NMR studies on LiRh₂Si₂ revealed restricted motional narrowing due to lithium atomic diffusion in the temperature range 170-450 K.< Leer menos